/*
 * Copyright 2002-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.core.log;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.impl.NoOpLog;

import java.util.List;
import java.util.function.Predicate;

/**
 * Implementation of {@link Log} that wraps a list of loggers and delegates
 * to the first one for which logging is enabled at the given level.
 *
 * @author Rossen Stoyanchev
 * @see LogDelegateFactory#getCompositeLog
 * @since 5.1
 */
final class CompositeLog implements Log
{

    private static final Log NO_OP_LOG = new NoOpLog();


    private final Log fatalLogger;

    private final Log errorLogger;

    private final Log warnLogger;

    private final Log infoLogger;

    private final Log debugLogger;

    private final Log traceLogger;


    /**
     * Constructor with list of loggers. For optimal performance, the constructor
     * checks and remembers which logger is on for each log category.
     *
     * @param loggers the loggers to use
     */
    public CompositeLog(List<Log> loggers)
    {
        this.fatalLogger = initLogger(loggers, Log::isFatalEnabled);
        this.errorLogger = initLogger(loggers, Log::isErrorEnabled);
        this.warnLogger = initLogger(loggers, Log::isWarnEnabled);
        this.infoLogger = initLogger(loggers, Log::isInfoEnabled);
        this.debugLogger = initLogger(loggers, Log::isDebugEnabled);
        this.traceLogger = initLogger(loggers, Log::isTraceEnabled);
    }

    private static Log initLogger(List<Log> loggers, Predicate<Log> predicate)
    {
        for (Log logger : loggers)
        {
            if (predicate.test(logger))
            {
                return logger;
            }
        }
        return NO_OP_LOG;
    }


    @Override
    public boolean isFatalEnabled()
    {
        return (this.fatalLogger != NO_OP_LOG);
    }

    @Override
    public boolean isErrorEnabled()
    {
        return (this.errorLogger != NO_OP_LOG);
    }

    @Override
    public boolean isWarnEnabled()
    {
        return (this.warnLogger != NO_OP_LOG);
    }

    @Override
    public boolean isInfoEnabled()
    {
        return (this.infoLogger != NO_OP_LOG);
    }

    @Override
    public boolean isDebugEnabled()
    {
        return (this.debugLogger != NO_OP_LOG);
    }

    @Override
    public boolean isTraceEnabled()
    {
        return (this.traceLogger != NO_OP_LOG);
    }

    @Override
    public void fatal(Object message)
    {
        this.fatalLogger.fatal(message);
    }

    @Override
    public void fatal(Object message, Throwable ex)
    {
        this.fatalLogger.fatal(message, ex);
    }

    @Override
    public void error(Object message)
    {
        this.errorLogger.error(message);
    }

    @Override
    public void error(Object message, Throwable ex)
    {
        this.errorLogger.error(message, ex);
    }

    @Override
    public void warn(Object message)
    {
        this.warnLogger.warn(message);
    }

    @Override
    public void warn(Object message, Throwable ex)
    {
        this.warnLogger.warn(message, ex);
    }

    @Override
    public void info(Object message)
    {
        this.infoLogger.info(message);
    }

    @Override
    public void info(Object message, Throwable ex)
    {
        this.infoLogger.info(message, ex);
    }

    @Override
    public void debug(Object message)
    {
        this.debugLogger.debug(message);
    }

    @Override
    public void debug(Object message, Throwable ex)
    {
        this.debugLogger.debug(message, ex);
    }

    @Override
    public void trace(Object message)
    {
        this.traceLogger.trace(message);
    }

    @Override
    public void trace(Object message, Throwable ex)
    {
        this.traceLogger.trace(message, ex);
    }

}
